Select the WRONG pair from the following

Options

A. 47, XXY - characteristic palm crease
B. trisomy of 21 - retarded mental and physical development
C. phenylketonuria - mental retardation
D. 45, XO - sterility

Answer

To solve the question of identifying the wrong pair from the given options, we will analyze each option step by step.

### Step 1: Analyze Option A
- **Option A** states that 47 chromosomes with the condition XXY is characteristic of a "palm."
- However, the correct condition for 47 chromosomes and XXY is actually known as **Klinefelter syndrome**, which occurs in males.
- Therefore, Option A is incorrect.

### Step 2: Analyze Option B
- **Option B** mentions that a trisomy of 21 causes Down syndrome.
- This statement is correct as Down syndrome is indeed caused by the presence of an extra chromosome 21 (trisomy 21).
- Therefore, Option B is correct.

### Step 3: Analyze Option C
- **Option C** states that phenylketonuria (PKU) causes mental retardation.
- This is also a correct statement, as PKU is a genetic disorder that leads to intellectual disability if untreated.
- Therefore, Option C is correct.

### Step 4: Analyze Option D
- **Option D** indicates that a 45 chromosome condition with an XO configuration (Turner syndrome) results in infertility or sterility.
- This statement is accurate, as individuals with Turner syndrome typically have one X chromosome and are often infertile.
- Therefore, Option D is correct.

### Conclusion
After analyzing all the options, we find that:
- **Option A** is the wrong pair as it incorrectly associates the XXY condition with "palm" instead of Klinefelter syndrome.

### Final Answer
The wrong pair is **Option A**: 47 chromosomes (XXY) is incorrectly labeled as characteristic of a "palm."

---